1. Field of the Invention
The present invention relates to a falsification detecting apparatus and system of video content, and particularly to a detecting apparatus, a detecting method, and a detecting program of an electronic watermark, and an integrity verification system and a structure of video content, by all of which falsification such as deletion, addition, and replacement of digital video content is detected through an electronic watermark.
2. Description of the Related Art
Digital video content is occasionally used as evidential video in court. However, if the digital video content is stored over a long period of time, it is necessary to prove that the stored video content is not different from the original one because it is easily modified. As techniques for proving the authenticity of content, an electronic signature technique and an electronic watermarking technique have been put to practical use.
Preparation of electronic signatures involves time and efforts to make in some cases because data are needed to be transmitted and received to/from a certificate authority under the environment of enhanced security. On the other hand, as for an electronic watermark, if the authenticity of content is proven by using an electronic watermarking technique, watermark information can be embedded into the whole content in a dispersed manner. Accordingly, even if a coding scheme is converted, the embedded watermark information is hardly erased. Therefore, in the case where content is to be stored over a long period of time, a method of proving the authenticity using the electronic watermarking technique is preferable.
As for usage of the electronic watermarking technique, a technique for embedding information into content including video data and voice data through an electronic watermark is disclosed in the Patent Publication 1 and the Patent Publication 2.
In the Patent Publication 1, in order to automatically correct time difference of video and voice that are being broadcasted or used, the same time information is inserted into synchronized digital video and digital voice as an electronic watermark on the transmission side. In the meantime, the time information extracted from the digital video and the digital voice is compared to each other on the reception side, so that time difference of the video and voice is detected and corrected in accordance with the comparison result.
In addition, in the Patent Publication 2, a characteristic value obtained from header information of content is embedded into video data or voice data through an electronic watermark on the transmission side, and the watermark information embedded into the content is extracted on the reception side. In the case where the extracted watermark information does not match the header information, falsification of the content is detected.
[Patent Publication 1] JP Laid-Open No. 2003-259314
[Patent Publication 2] JP Laid-Open No. 2003-122726
[Non-Patent Publication]
“I. Echizen, H. Yoshiura, T. Arai, H. Kimura, T. Takeuchi: General Quality Maintenance Module for Motion Picture Watermarking, IEEE Trans. Consumer Electronics, Vol. 45, No. 4, pp. 1150-1158, (1999)”